Cloacogenic carcinoma.

Cloacogenic carcinoma is a rare tumor of the anorectal region originating from a persistant remnant of the cloacal membrane of the embryo. The tumor accounts for 2-3% of anorectal carcinomas and occurs more than twice as often in women. Most tumors present as fungating or ulcerating lesions, but the tumor may arise in anal ducts and present as a submucosal mass. Wide abdominoperineal resection is the treatment of choice with a five year survival of 50%. Metastases occurs to the inguinal lymph nodes in more than 50% of the patients at sometime during the course of the disease with distant metastases occuring most commonly to liver and lungs.